This invention relates to residential sewage pumping systems for use in discharging sewage from a source of origin, such as a residence, into a sewer main.
In urban environments, residential sewage is generally discharged from a residence through a gravity fed system into a sewer main. Thus the slope of the system conduits is continuously downward from the residence to the sewer main. Such systems are not only expensive to install but are sometimes impossible to install in hilly terrain without the use of lift pumps to lift the sewage from one point in the system to another.
Other residential sewage systems, most commonly those used in suburban or rural environments, use septic systems. Such residential sewage systems include a septic tank and a dry well or drain field for disposing of the excess waste water. Such systems cannot be used in all locations due to rocky soil, heavy non-absorbent soil, or due to environmental considerations.
Still other residential installations have used pressure sewer systems. Pressure sewer systems discharge the sewage from a residence and the like by means of a pump to a common force main or to a gravity main located in the street. Such pressure sewer systems have commonly used effluent pumps or grinder pumps, both of which use an impeller with a plurality of vanes to transport the sewage under pressure from an inlet conduit to an outlet conduit. Grinder pumps differ from effluent pumps in that they additionally have a cutting element to grind or comminute the sewage prior to pumping the sewage. Grinder pumps have not been satisfactory since they require extremely high maintenance, especially with regard to the cutting elements. Furthermore, the cutting elements tend to clog if the sewage contains cigarette filters, plastic straws or other plastic non-soluble items such as panty hose, or infant diaper moisture barriers.
Another problem with such systems is that vane type pumps are limited in the amount of lift which they can provide. Commonly, such systems are limited to providing to forty (40) feet of lift. If it is attempted to increase the lift generated by such vane type pumps, the seals of the pumps tend to fail due to excessive pressure generated in the pumps, thereby resulting in expensive repairs. Even without excessive pressures in the system, another problem with such pressure type sewer systems has been that pump maintenance has been relatively expensive. The seals of the system tend to wear out after a period of use and replacement of the seals requires disassembly of the pumps.
Another problem with prior art pressure sewer systems has been that the check valves used in the system are subject to becoming stuck, thereby causing complete failure of the system. Commonly such prior art pressure sewer systems include a single check valve to isolate the system from the force sewer main or gravity sewer main. It is possible that large debris, such as for instance, infant diapers, may become lodged in the check valve, thereby completely disabling the system and requiring clearing of the check valve.
It is therefore desired to provide a residential pressure type sewer system which is relatively inexpensive to maintain, which provides a substantial amount of lift, and wherein the pump is inexpensive to maintain and not subject to failure. Furthermore, it is desired to provide such a system wherein the size of the solids which can be handled by the system is substantially greater than in the prior art systems.
Lastly, it is desired to provide a system wherein the check valves are not subject to being disabled whereby the system will continue to function even though one of the check valves may be stuck in the open position.